In many deposition chambers, both atomic layer deposition and chemical vapor deposition, rotating pedestal/heaters are used to improve non-uniformity. In most cases, non-uniformity comes from non-uniform chemical delivery, flow distribution, chamber features, and temperature non-uniformity from the chamber body and surrounding components. Using a rotating pedestal can distribute the local effect of these variations and improve the non-uniformity.
However, in some cases, non-uniformity can be contributed by the pedestal or the heater itself, especially when the substrate (wafer) sits on or contacts the heater. The impact of local non-uniform temperature distribution can have a significant impact on the uniformity of deposition. This non-uniform temperature distribution can come from heater element layout, local features like lift pin holes, non-uniform radiative heat loss, non-uniform contact surface or gap, or other reasons.
Therefore, there is a need in the art for apparatus and methods to eliminate or reduce local non-uniform temperature distribution resulting from pedestal/heater to substrate contact.